A so-called head-up display (HUD) device which projects video image light onto a windshield of an automobile to form a virtual image and which displays traffic information such as route information and traffic jam information, and automobile information such as a fuel level and a cooling water temperature has already been known by Patent Document 1 described below.
In this type of information display device, it has been required that virtual images are respectively formed at a plurality of positions according to a visually recognized position of a driver, in other words, a distance of forming the virtual image is adjusted to the visually recognized position of the driver in order for the driver to easily recognize the information. Thus, as also disclosed in Patent Document 2 described below, for example, the images are formed far (at a long distance) and near (at a short distance) from the driver.